The present invention relates to a secondary battery, and the secondary battery according to the present invention comprises: an electrode assembly in which first electrodes, separators, and second electrodes are alternately stacked on one another; and a can for accommodating the electrode assembly, wherein the first electrodes have first electrode uncoated portions, which are not coated with the electrode active material, disposed at ends of one sides thereof so as to protrude farther than the separator with respect to a central axis in a direction where the electrode assembly is wound, the second electrodes have second electrode uncoated portions, which are not coated with the electrode active material, disposed at ends of the other sides thereof so as to protrude farther than the separator with respect to the central axis in a direction where the electrode assembly is wound, and the can comprises a first can and a second can. The first electrode uncoated portions contact a first connection portion provided at an end of one side of the first can, the second electrode uncoated portions contact a second connection portion provided at an end of the other side of the second can, and at least one of the first connection portion and the second connection portion includes a protrusion connection portion having a form protruding towards the electrode assembly.